I was listening to the audio of a debate between a Christian pastor and an atheist. The pastor is Bob Thune, who is the head pastor at Corem Deo Church, in Omaha, NE. I typed out his answer to a couple questions below. You can listen to the audio here. I would highly reccomend it.
Question: Can you name one moral or ethical act that you think cannot be performed by a non-believer?
Answer: There is no moral or ethical act that cannot be performed by a non-believer. Ethics is a human thing not a distinctively Christian thing. Humans are made in the image of God. So the fact that we are human means every human being has the capability to perform ethical acts. Non-believers can sometimes be more moral than believers.
Christianity is not a religion that believes that people are saved based on their ethical obedience. Rather Christianity is a religion that acknowledges and admits human brokenness in the world. Christianity encourages us to look to Christ for salvation and for restoration to the image of God. So my answer to the question is nothing.
On the other hand my answer to this question is everything. The bigger question is what makes an act ultimately good? Why should I live an ethical life? The ultimate standard for ethics is not what we think is right or good, but that we should live for the glory of God. By this estimation, every act would be judged by human criteria of ethics or morality, but is it done with the intent of worship to and glory toward God? By that capacity only a believer would have the capacity to act in a way that is glorifying God.
Conclusion: It is possible for nonbelievers and all human beings to act ethically in a limited sense for the good for human society. But in the ultimate sense, we have to refer to the higher question of what defines the ultimate standard of reality, and that is the glory of God.
Question: Can you have morals without believing in the Christian deity?
Answer: I think you can have morals without believing in the Christian deity, because morals have very little to do with what you believe or don’t believe, and a whole lot to do with what is exactly true about the human condition and what it means to be a human person.
You can have morals without believing in the Christian deity, however, you cannot have morals without the existence of a deity. If there is no God you can have no basis for morality. All moral judgments assume an absolute moral vantage point. Anytime someone says should or should not is making an absolute ethical obligation. And such statements can only be made if there is some external vantage point outside of us that can ground those statements.
Obviously not all of us believe in the existence of a deity, but we all believe that people should and shouldn’t act in certain ways. Anyone who has a morality is borrowing from the Christian tradition whether they know it or not. It is not possible to make any moral judgement except borrowing from the Christian worldview by making that judgement. You can absolutely have morals without believing in the Christian deity, but you cannot have morals without the existence of a deity.